Easy answer (

), RoS:

In Excel (or some such), set your zoom really low to start with. Highlight the whole sheet, and make your rows and columns the exact same height/width in pixels - this gives you a square grid. Use the drawing objects to make a circle 250 rows high.

Make the thing transparent, so you can get to the boxes underneath. Put a value in the first and last boxes that are actually inside the circle in each row. Then (and you will have to zoom back in for the answers) use formulae to calculate the number of columns (remember to make it inclusive of the ones with values) for each row.

Multiply the answer by 4 (because you made your boxes=4m). Then use pie are square. Now you have the area for each deck, a simple sum will give the total. The advantage is you only write the formula once, then use auto-fill to populate the rest of the decks.

I am currently designing a belter for my Quaddies (0-g folks), that is a sphere, with 6 cylinders coming out from it. I needed to figure how much of the sphere was needed to hold some of the fuel, and used this idea to see when (going down from one "end") I had enough room. I used .1m high sections in a 7.5m radius sphere.

If you want to PM me RoS, I can pull that worksheet and e-mail it to you (may save you

*some* work).